Multi-ply valve sacks



Sept. 25, 1956 w v, QWENS 2,764,339

MULTI-PLY VALVE SACKS Filed July 17, 1950 2 Sheets-Sheet 2 f z E; 46 4740 4] 2,764,339 1C6 Patented Sep ,5 1956 MULTI-PLY VALVE SACKS WilliamVincent Owens, London, England, assignor to Paper Sacks Limited,Bristol, England Application July 17, 1950, Serial No. 174,170 Claimspriority, application Great Britain July 20, 1949 5 Claims. (Cl. 229-55)This invention relates to multiply paper blockbottom valve sacks or bags(hereinafter referred to as bags) and their manufacture, of the typewherein the plies at each face of the flattened bag tube length arearranged so that the ends thereof progressively overlap to providestepped or staggered margins, those of the flap of one face beingadhesively secured to those of the flap 0f the other face, in foldingthem to form the blockbottom closure. The invention also relates tomultiply blockbottom bags of the above character comprising three ormore plies, wherein the bag tube lengths are ruptured from a continuousmultiply bag tube formed on the bag tubing machine by the assemblytherein of the several webs for the plies which have been perforatedtransversely normally across the full width of the webs and slitlongitudinally without waste of paper, to provide notched and shoulderedrupturing lines for forming the stepped margins, the rupturing beingaccomplished by tensioning each leading bag tube length.

Certain blockbottom bags of the stepped margin type have beenmanufactured andrvarious proposals have been made for making blockbottomclosures in bag tube lengths, but all these have involved a modificationof the normal diamond corner fold of the blockbottom, such that the endclosures could not be carried out on one or other of the standardblockbottom forming machines in which the bag tu'belengths continuouslytravel through the folding means, but had to be treated in machines inwhich the bag tube was halted .at each folding stage.

Furthermore, although these stepped margin bags possessed a satisfactoryadhesive seal transversely across the bag mouth at the several plies oneto the other by virtue of the stepped end margins, the adhesive seal atthe triangular fold of the corners of the bagwere imperfect or weak suchthat'sifting of the contents of lthe bag's'might occur through thecorner folds, 'as the stepped margins are covered or partially coveredby the outer ply at the triangular fold, such that adhesion occurredonly or mainly with the outermost ply of .said triangular -folds.

"It'will be appreciated that with a stepped margin blockbottom bag, thestepping at one end is thefreverse of that at the other and while at oneend the inner plies at the triangular fold are exposedforpartly exposed)affording flexibility and a good adhesive closure, at the other end theouter ply 'covers'the margins of the inn'er'plies at "the triangularfold 'and hence only one ply is available for adhesively securing to theflap folds and the present invention is directed'to overcome "thisobjection.

The aim of the present invention is to remove vdefects of the abovecharacter and toprovide for the manufactureof a multiply steppedmarginfbag, wherein the blockbottom closure is adhesively sealed notonly to more than onetply at the stepped end transverse margins of theface flaps, but also at two or more plies'at the corner fold, andfurthermore wherein the blockbottom closure is of the normal orstandarddiamond cornert-ype capable of being adhesively closed on a blockbottommachine of the continuous folding character referred to above.

The invention consists in a method of manufacturing multiply steppedvalve bags for diamond fold blockbottom closure, by slitting andperforating paper webs for the plies of the bag tube on rupturing linestransversely of the web characterised in this that a ply (or plies) isslit and perforated to outline a recess and a complementary tongueprojecting longitudinally beyond the outermost ply at diagonallyopposite corners of the bag tubes and extending laterally to orbeyond'the transverse folding lines of the face flaps, and folding theends of the tubes to diamond blockbottom form in .a continuousblockbottom machine with adhesive sealing, including the projectingtongues, to more than one ply at all the corners except a valve foldcorner. I

According to the invention a pair of diagonally opposite tongues may beformed on one ply only or one tongue may be formed on one ply and theother tongue on another ply, or two pairs of diagonally opposite tonguesmay be provided, one pair being on one ply (or distributed between twoplies) and the other pair may be on another ply (or distributed betweentwo plies). .Where more than one tongue provided at any one corner, thaton the inner ply is dimensioned longitudinally to project at thetriangular fold beyond the other tongue so as to expose a margin foradhesive sealing. 1

It is known according to British patent specification 'No. 623,313 toprovide a projecting integral tongue by the perforating and slittingmethod at a valve fold for the purpose of providing a flexible marginwhich operates to prevent sifting of the contents through the valveopening and .in carrying out the present invention it is preferred toembody such tongue in the bags on .an appropriate ply including theoutermost for the same purpose.

A further feature of the invention resides in the formation of anintegral label-like cover flap on the outermost ply for adhesive sealingover the stepped flap andovera portion ofthe diamond corner folds, thiscover flap being formed by perforating and slitting the outermost :plyweb on a shouldered and notched line. At one end of the duced by theslitting, and the other may he produced by interrupting the paste andleaving av'free end of the longitudinal edge .of the seam the remainderof which is adhesively secured in forming the outer bagtube.

In the accompanying drawings:

Figure 1 illustrates .a series of plies fora 4- ply.bag arranged instaggered relation.

Figures 2 to 4 show the various folding steps to form the diamondblockbottom.

Figures 5 to .8 are similar views showing the invention .applied to a.3-ply staggered margin bag.

Figures 9 to 12 are similar views showing the invention vapplied to a 5-ply bag.

Figures 13 and 14 are views showing the invention as applied to only onecorner of the bag.

In certain of the figures -.the configuration .of the :plies isindicated by using dash, dasheand dot, dash-.and two dots, etc. to showparts that are to the rear of amouter ply. s

In carrying the invention into effect ,in constructing a 4-plyblockbottom bag having integral ;pl y extensions verse perforations andlongitudinal slittings'to 'form the shoulders and notches .in the endmargins 1a, ,2a, 5a

and 4a, to which will :,give the (appropriate; staggering or stepping ofsuch ends when the webs ,are ,folded over about the lines1c--;c and:d--d' toform aitube.

d-d-takes place beneath the intermediate portions between said lines. Ii

. The innermost ply but one of the bag, i. e. ply 3, is-"formed with atongue or integral ply extension which will lie at one corner of the bagtube and a tongue or integral ply extension 6 which will lie at theopposed diagonal corner of the tube. These tongues 5 and 6 will projectbeyond the outermost ply 1 of the tube, i. e; beyond the normaltransverse end lines of the tube length.

Corresponding to the tongues 5 and 6 the ply 3 will be provided withrecesses 5a and 611. Thus the tongues will be'formed on-succeeding baglengths without waste of material.

When the plies 1, 2, 3 and 4 are folded about the lines c-c an'd dd andthe longitudinal edge margins 1b, 2b, 3b, 4b and 1c, 20, 30, 4c, areadhesively secured to form the nested tubes and the bag length issevered by a longitudinal pull thereon, the tongues 5 and 6 will befolded in half about the lines cc and dcf and will be provided atdiagonally opposite corners of the bag length. The valve may be formedat either of said corners.

The ends of the bag length are formed into diamond blockbottoms bynormal continuously operating blockbottoming mechanism.

The first step in forming the diamond blockbottom 1s illustrated inFigure 2 by which triangular corners 7, 8, 9 and 10 are formed.

At the corner 8 at which the valve may be formed 7 the tongue 5 projectsbeyond the normal edges 11 of the corner and will provide an improvedvalve construction as it provides a flexible projection preventingsifting through the valve.

Similarly at the corner 9 the tongue 6 extends beyond the normal edges12 and thus provides additional pasting area where normally thestaggered margins are masked. The tongue will thus be a two-ply lock atthis corner whereas normally, owing to the masking the corner is onlyone-ply strong as the pasting in closing the corner would necessarily belimited to the masking triangular portion.

At the other corners 7 and 10 the recesses 6a and 5a provide greaterflexibility and as the areas 13 and 14 of the innermost ply 4 areexposed by the recesses for pasting purposes they also facilitate themaking of sift proof closures.

In the next stage of closing shown in Figure 3 in which the sideportions 15, 16 are folded over about the lines 17, 18 it will be notedthat portions of the tongues 5b and 6b are still exposed after the foldis made and such exposed portions provide additional paste receivingareas available for the final fold, thus providing improved adhesion ofthe staggered parts.

At the other corners 7 and 8 there is still a considerable area of theinner ply 4 exposed for pasting when the final fold is made.

The final fold is illustrated in Figure 4 in which the side portions 19and 20 are folded over about the lines 21, 22.

In this final fold it will be noted that the outer ply is formed with anintegral sealing label 23 for providing a sift proof corner closure,avoiding the necessity of supplementary labels for the purpose.

This integral sealing label 23 is formed by slitting the outer ply 1longitudinally a distance conforming to diamond edge 24 (FigureZ) at onecorner 7 and by interrupting the paste line at the longitudinal seam orjoin at the other corner 8.

At the lower corners 9 and '10 the slitting must be 4 effected at bothcorners as the seam lies on the inner side of the folded end.

The position for the slits in forming the integral label may be variedin relation to the longitudinal folds of the bag.

It will be noted that the width of the tongues 5 and 6 is such that thetongue extends laterally beyond the transverse folding lines 18 and 21of the face flaps 15, 16, 19, 20, but the tongues may be narrower ifdesired provided the desired adhesion area is obtained.

The invention is illustrated in Figures 5 to 8 as applied to a 3-plybag.

In this bag the intermediate ply 25 is provided with extension tongues26, 27 which will be located at diagonally opposite corners of the bagand corresponding recesses 28, 29 which are located at the othercorners.

In the first fold illustrated in Figure 6, by which the triangularcorners 30, 31, 32, 33, are formed, the tongues 26, 27 provide thestaggering and additional exposed areas at corners 31, 32, while therecesses 28, 29, at corners 33, 30, provide an increased exposed area ofthe innermost ply 34.

The outermost ply 35 is also slit longitudinally and has an interruptedpaste area at the longitudinal join at one end of the bag length to formthe sealing labels 36, 37.

The further folding to form the diamond blockbottom is illustrated inFigures 7 and 8, all stages of the folding being effected on acontinuous operation blockbottoming machine.

In applying the invention to a 5-ply bag, see Figures 9 to 12, tongueextensions may be applied to two of the plies thus providing a 3-plylock at the corner which is normally only l-ply strong.

Referring to Figure 9 the third and fourth plies 38, 39 are formed withtongues 40, 41 at one corner position and tongues 42, 43 at thediagonally opposite corner position. At the other corner positionscorresponding recesses 44, 45, 46, 47 are formed.

When the first fold to form the blockbottom is made, see Figure 10, itwill be noted that at the corner the two tongues 40, 41 are exposedproviding the 3-ply lock at the corner which is to be sealed. At theother corners 50, 51 an increased sealing area of the innermost ply 52is provided.

The outer ply 53 is formed with sealing labels 54, 55 by longitudinalslits as described in the previous examples.

The further stages of folding are shown in Figures 11 and 12 and hereagain all folding steps to form the diamond blockbottom are effected bycontinuously operating blockbottoming mechanism.

Figures 13 and 14 illustrate the application of the invention in whichthe tongue or integral .ply extension is formed at one corner only, thecomplementary corner being provided with a recess.

Thus the tongue 56 is formed on the ply 57 which is the innermost plybut one of the bag. At the other end of the bag a corresponding recess58 is formed.

The corner 59 having the tongue 56 may be the valve corner of the bag.

The outermost ply 60 is also formed with a label flap 61 as in theprevious modification.

The blockbottom folding is effected on a continuous operation machine,the first fold being shown in Figure 14. The second and final folds areas in the modification already described.

Where the bag is provided with more than three plies the integral plyextensions or tongues may be provided at all four corners in which casetwo tongues are formed on one ply at diagonally opposite corners whilethe other tongues are formed on another ply at the remaining corners.

In multiply bags formed with integral tongues according to the inventionit will be found that the improved formation at the closed cornersrenders them siftproof whereby the necessity of supplementary labels isavoided thus effecting a considerable saving in labour, material andplant.

Moreover, such siftproof qualities are increased by the provision of theintegral label flap on the outer ply of the sack which again beingformed integral without waste of material avoids the necessity ofsupplementary labels.

The formation of the integral label closure also avoids the springinessof the final corner fold as it reduces the thickness at this fold.

I claim:

1. A multi-ply stepped margin diamond corner blockbottom bag comprisingat least three substantially coextensive nested and flattened tubelengths each having a longitudinal seam displaced laterally from theseams of the other tube lengths, a diamond corner fold closure at eachend of the set of tube lengths, the terminal edges of the tube lengthsat each end of the bag being stepped with respect to one anotherthroughout the lengths of said edges; an intermediate one of said tubelengths having at one end, located in one corner fold, a tongueprojecting beyond the edge of the overlying tube length, and at itsother end located in the corresponding corner fold, a recesscorresponding to said tongue in shape and position; the stepped edges atthe bag ends being folded one set over the other and adhered to oneanother with the projecting portion of said tongue being adhered toportions of the other tube lengths.

2. A multi-ply stepped margin diamond corner blockbottom bag inaccordance with claim 1, in which said intermediate one of said tubelengths has an additional projecting tongue located in the diagonallyopposite corner told from the first-named tongue, and a correspondingrecess at the remaining corner fold.

3. A multi-ply stepped margin diamond corner blockbottom bag comprisingmore than three substantially coextensive nested and flattened tubelengths each having a longitudinal seam displaced laterally from theseams of the other tube lengths, a diamond corner fold enclosure at eachend of the set of tube lengths, the terminal edges of the tube lengthsat each end of the bag being stepped with respect to one anotherthroughout the lengths of said edges; a first intermediate one of saidtube lengths having at one end, located in one corner fold, a tongueprojecting beyond the edge of the overlying tube length, and at itsother end, located in the corresponding corner fold, a recesscorresponding to said tongue in shape and position; a secondintermediate one of said tube lengths having, at the end opposite thetongue of the first intermediate tube length, and located at thediagonally opposite corner fold, a similar projecting tongue, and acorresponding recess at the other end of the second intermediate tubelength in the remaining corner fold; the stepped edges at'the bag endsbeing folded one set over the other and adhered to one another with theprojecting portions of said tongues being adhered to portions of theother tube lengths.

4. A method of making multi-ply stepped valve bags for diamond foldblock-bottom closure, comprising the steps of slitting and perforating aplurality of at least three laterally-offset webs to definesubstantially superposed panels having both their lateral andlongitudinal margins stepped with respect to one another, folding eachset of superposed panels about spaced longitudinal lines to superposethe longitudinal edges of respective plies thereof and adhering saidedges each to each to form nested tubes with staggered seams, theperforations being so disposed in the respective plies as to definelongitudinally stepped margins at both bag ends when the tubes aresevered into individual lengths; at least one intermediate panel beingslitted and perforated to define at each end, in the region ofdiagonally opposite corner folds, a tongue projecting beyond the lateralmargins of the other panels and at the end opposite each tongue acorresponding recess; pulling said tubes lengthwise to separateindividual bag lengths from the remainder of the tube, and thereafterfolding and adhesively sealing the ends of the respective individuallengths of nested tubes to diamond block-bottom form, including sealingthe projecting tongue at at least one end to more than one of the otherpanels.

5. The method in accordance with claim 4, in which two intermediatepanels are so slitted and perforated, to provide such tongues andrecesses at complementary corner fold regions of said respective twointermediate panels.

References Cited in the file of this patent UNITED STATES PATENTS1,935,380 Smithurick Nov. 14, 1933 2,013,086 Baker Sept. 3, 19352,055,030 Hoppe Sept. 22, 1936 2,176,499 Hoppe Oct. 17, 1939 2,246,911Baker June 24, 1941 2,360,720 Robinson Oct. 17, 1944 2,460,885 HoppeFeb. 8, 1949 2,488,038 Sharkey Nov. 15, 1949 FOREIGN PATENTS 343,447Great Britain Feb. 10, 1931

